Re: [PATCH 05/18] Add io_uring IO interface

[Jens Axboe <axboe@kernel.dk>]

On 1/29/19 5:12 AM, Florian Weimer wrote:
> * Jens Axboe:
> 
>> +#define IORING_MAX_ENTRIES	4096
> 
> Where does this constant come from?  Should it really be exposed to
> userspace?

Seems pretty handy for the application to know what the limit is?

>> +struct io_uring_params {
>> +	__u32 sq_entries;
>> +	__u32 cq_entries;
>> +	__u32 flags;
>> +	__u16 resv[10];
>> +	struct io_sqring_offsets sq_off;
>> +	struct io_cqring_offsets cq_off;
>> +};
> 
>> +struct io_sqring_offsets {
>> +	__u32 head;
>> +	__u32 tail;
>> +	__u32 ring_mask;
>> +	__u32 ring_entries;
>> +	__u32 flags;
>> +	__u32 dropped;
>> +	__u32 array;
>> +	__u32 resv[3];
>> +};
>> +
>> +struct io_cqring_offsets {
>> +	__u32 head;
>> +	__u32 tail;
>> +	__u32 ring_mask;
>> +	__u32 ring_entries;
>> +	__u32 overflow;
>> +	__u32 cqes;
>> +	__u32 resv[4];
>> +};
> 
> Should the reserved fields include a __u64 member, to increase struct
> alignment on architectures that might need it in the future?

Sure, I can do that.

>> +#define IORING_ENTER_GETEVENTS	(1 << 0)
> 
> Should this be unsigned, to match the u32 flags argument?  (Otherwise
> using 32 flags can be difficult).

Good point, I've changed them all to be unsigned.


-- 
Jens Axboe